Orthopedic device

ABSTRACT

An orthopedic device for the orthotic or prosthetic provision of a patient is provided. The orthopedic device includes a knee joint, which has a proximal upper part and a distal lower part arranged pivotably thereon, an ankle joint, a pivoted foot part which can be fastened distally to the ankle joint, and a shin part arranged between the ankle joint and the knee joint. The upper part of the knee joint or a thigh part fastened thereto that can be attached to the patient&#39;s body and is coupled with the foot part by means of a force transfer device, which causes a plantar flexion of the foot part when a knee is flexed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.15/976,636, filed 10 May 2018, and entitled ORTHOPEDIC DEVICE, issued on19 Jan. 2021 as U.S. Pat. No. 10,893,959, which is a continuation ofU.S. patent application Ser. No. 14/646,705, filed 21 May 2015, andentitled ORTHOPEDIC DEVICE, issued on 12 Jun. 2018 as U.S. Pat. No.9,993,356, which is a U.S. National Entry Application from PCTInternational Patent Application No. PCT/EP2013/003567, filed 26 Nov.2013 and also entitled ORTHOPEDIC DEVICE, which claims the benefit ofGerman Patent Application No. 102012023023.0, filed 26 Nov. 2012, thedisclosures of which are incorporated, in their entireties, by thisreference.

TECHNICAL FIELD

The invention relates to an orthopedic device for the orthotic orprosthetic provision of a patient, with a knee joint, which has aproximal upper part and a distal lower part arranged pivotably thereonabout a knee axis, and an ankle joint with an ankle joint axis, a footpart which is arranged distally on the ankle joint and is pivotableabout the ankle joint axis, and a shin part arranged between the anklejoint and the knee joint. The device can be fastened to the body of thepatient via a thigh component arranged proximally on the knee joint.

BACKGROUND

The purpose of orthoses is to guide or support the movement of anexisting limb or to brace and support the limb, while prostheses replacelimbs that are not present. Leg orthoses are available in differentembodiments, with those referred to as knee angle foot orthoses (KAFO)supporting both the foot and also the ankle joint and knee joint. Thefoot is generally placed on a foot plate, one or more shin rails extendparallel to the lower leg, a knee joint is provided approximately in thearea of the knee axis, and fastening devices are mounted on one or morethigh rails in order to fasten the prosthesis to the upper leg.Likewise, fastening devices can be provided on the shin rails and on thefoot plate so as to be able to fasten the orthosis on the respectiveleg.

Prosthetic devices with a prosthetic knee joint have a prosthetic foot,which is fastened to the prosthetic knee joint via a lower leg tube.Proximally from the prosthetic knee joint, a fastening device isprovided for the prosthesis, which is usually designed as an upper legsocket into which the upper leg stump can be inserted. A prosthetic kneejoint can have various designs ranging from a monoaxial prosthetic kneejoint or a polycentric knee joint with damping means to computer-aidedor driven active prosthetic knee joints. The prosthetic feet can befastened to the lower leg tube either rigidly or in an articulatedmanner, while motor-driven prosthetic feet are also possible.

FR 2,549,719 A1 relates to a prosthesis with a prosthetic knee joint andwith a prosthetic foot fastened to a lower leg tube in an articulatedmanner. A connection rod, which is coupled to the prosthetic knee jointvia a lever mechanism, is arranged posterior to the ankle joint axis.When the prosthetic knee joint is flexed, the prosthetic foot is liftedand a dorsiflexion is performed.

US 2008/0269913 A1 relates to an artificial leg with a prosthetic kneejoint and a prosthetic foot. On the prosthetic knee joint, a connectionrod is articulated frontally with respect to the knee joint axis, suchthat, upon flexion of the knee, the connection rod is moved in a guidein the lower leg tube. The movement is conveyed to the prosthetic footvia a tensioning element, such that the tip of the foot is lifted in theknee flexion.

US 2009/0265018 A1 relates to a driven leg prosthesis and to a methodfor controlling the leg prosthesis in order to achieve an almost naturalgait pattern. Both the prosthetic knee joint and also the ankle jointare provided with separate motor drives. The prosthesis is controlled inreal time by sensors on the basis of different intramodal controlprograms.

EP 0 041 052 B1 relates to a prosthesis for a lower limb, in which anupper leg socket and a lower leg are coupled to each other via a toothedhinge. A spring-loaded piston rod lifts the toes in the event of a kneeflexion.

DE 47 53 03 B1 relates to an artificial leg in which a lower leg partand an upper leg part are connected to each other by two articulatedrods, in order to effect a dorsiflexion when the prosthetic knee jointis angled.

In prosthetic devices with a functional separation of knee joint andankle joint, damping is often provided during the movement, such thatthe kinetic energy is converted to thermal energy. If there is afunctional connection of knee joint and ankle joint, the kinetic energyis conveyed from the knee joint to the ankle joint.

SUMMARY

The object of the present invention is to make available a couplingbetween the knee joint and the ankle joint with the least possibleoutlay in terms of design, which coupling allows the kinetic energy ofthe knee to be used for the ankle movement, provides an approximation tothe natural gait pattern and, at the end of the stance phase, minimizesa vertical movement of the center of gravity of the body.

According to the invention, this is achieved by an orthopedic devicehaving the features of the main claim. Advantageous embodiments anddevelopments of the invention are disclosed in the dependent claims, thedescription and the figures.

In the orthopedic device according to the invention for the orthotic orprosthetic provision of a patient, with a knee joint, which has aproximal upper part and a distal lower part arranged pivotably thereon,in particular about a fixed or instantaneous knee axis, and an anklejoint, which in particular has a fixed or instantaneous ankle jointaxis, a pivotable foot part which is arranged distally on the anklejoint, and a shin part which is arranged between the ankle joint and theknee joint, provision is made that the upper part of the knee joint, ora thigh part that is fastened thereto, is coupled to a foot part via aforce transmission mechanism, which causes a plantar flexion of the footpart when the knee is flexed. By coupling the upper part of the kneejoint, or a thigh component which is arranged proximally on the kneejoint and can be fastened to the patient's body, for example an upperleg rail or an upper leg socket, to a foot part via a force transmissionmechanism which causes a plantar flexion of the foot part when the kneeis flexed, it is possible to use the kinetic energy of the knee for theankle movement. Analogously to the natural gait pattern, in which aplantar flexion is performed at the end of the stance phase in order tolengthen the length of the leg upon flexion of the knee, the foot partundergoes plantar flexion by way of the force transmission mechanism. Inthis way, the duration of the ground contact of the foot part isprolonged, as a result of which the vertical movement of the center ofgravity of the body is minimized. By the energetic coupling of the kneeflexion with the plantar flexion of the foot part, a high energyefficiency is achieved with low outlay in terms of equipment. When theknee joint is extended during the swing phase, a movement reversal cantake place, such that a dorsiflexion of the foot part is brought about.Likewise, after a predetermined flexion angle is reached, the actuationof the prosthetic foot can be switched, such that, after the flexionangle is reached, a dorsiflexion is performed in order to reduce theeffective leg length and, in the swing phase, particularly when bringingthe foot forward, to prevent stumbling or catching on obstacles. Aplantar flexion is understood as that movement in which a pivoting ofthe foot part in the direction of the ground takes place, such that theangle between the shin part and the foot part increases. Dorsiflexion isthe opposite movement, in which the dorsum of the foot or the instep ismoved in the direction of the tibia or the shin part and the anglebetween the dorsum or instep and the shin part decreases. The pivotableconnection between the individual components can be realized via asingle fixed shaft, i.e. an axle that allows only a rotation movementand is secured in a stable position on at least one of the components.Alternatively, in the case of polycentric joints, a displaceableinstantaneous rotation axis can be realized which, on account of thepolycentric bearing in multi-link joints, is not stationary relative toat least one component but instead migrates in the course of thepivoting movement. A virtual rotation axis arises about which the upperpart pivots relative to the lower part or the shin part pivots relativeto the foot part. It is also possible that the pivotable attachment oftwo components to each other is effected via an elastomer joint, suchthat no defined fixed rotation axis is present, and instead differentrotation axes form within the elastomer joint under different loads, forexample in the event of different transverse forces or torsional forcesabout an axis that extends in the proximal-distal direction.

The force transmission mechanism can be designed as a hydraulic system,such that a very compact and easy transmission of force from the kneejoint to the foot part can take place via piston rods, hydraulic linesand valves. Likewise, the switch from plantar flexion to dorsiflexioncan be performed very easily via a switch valve, which can be controlledmechanically or also electrically. Alternatively or in addition, amechanical coupling mechanism can be provided that can be designed totransmit tensile force and/or compressive force. Mechanical couplingmechanisms have the advantage of a solid construction with a high degreeof availability and easy repair possibilities. On account of the movedparts in a mechanical coupling, items of clothing or prosthetic liningsmay tear or become caught.

The mechanical coupling mechanism can be mounted on a first bearingpoint protruding dorsally or ventrally with respect to the knee axis andmounted on a second bearing point ventrally or dorsally with respect tothe ankle joint axis, wherein the bearing points lie on different sidesof a connection line between a knee axis and an ankle joint axis. In thecase of a dorsally protruding first bearing point, the couplingmechanism is subjected to pressure during a flexion of the knee andtransmits the forces at the end of the stance phase to the secondbearing point lying ventrally with respect to the ankle joint axis, suchthat a moment arises about the ankle joint axis. In a reversearrangement of the first bearing point, i.e. ventrally with respect tothe knee axis, the moment is generated via a coupling mechanism thattransmits tensile force.

The mechanical coupling mechanism can be designed as an articulated rodor tensioning means, depending on how the arrangement of the couplingmechanism on the upper part and on the foot part is configured. In adesign as an articulated rod, it is possible that, up to a certain kneeangle, the articulated rod permits a transmission of compressive forceor also a transmission of tensile force, and, after the predeterminedknee angle is reached, the articulated rod is buckled at the joint suchthat no appreciable transmission of force can take place any longer or areversal of the direction of force takes place. The knee joint angle atwhich the articulated rod buckles is derived from the geometricrelationships between the upper articulation point of the couplingmechanism and the lower articulation point and, if appropriate, apretensioning of the joint. Starting from an initial position, thearticulated rod can be buckled only in one direction, such that, beforethe predetermined knee joint angle is reached, a safe transmission offorce is always possible and a reversal to the initial position cansafely take place. The ankle joint can be pretensioned in a dorsiflexiondirection in order to be able to effect a dorsiflexion in the absence ofthe force introduction via the coupling mechanism or the hydraulicsystem without reversal of the force direction.

To be able to make an adjustment to the wishes of the patient and to thephysical circumstances presented by the latter, at least the firstbearing point is designed to be adjustable, such that the distance ofthe first bearing point from the knee joint axis or the ankle joint axisis adjustable. In addition to the distance, the position in relation tothe respective axis can also be adjustable, so as to be able to adjustthe degree of displacement or plantar flexion of the foot part inaccordance with the flexion of the knee. Depending on the lever ratio, agreater or lesser plantar flexion can be adjusted.

In a hydraulic force transmission mechanism, a control mechanism and ifappropriate a switch valve can be provided in order to permit orinterrupt a force transmission. The interruption of the enablement ofthe force transmission can take place on the basis of sensor values, anangle setting and/or a particular load situation, for example inaccordance with the knee angle, the ankle joint angle or measured forcesor moments. The control mechanism can be controlled either mechanicallyor electrically. In the case of a mechanical control, a controlmechanism can be attached for example to the knee joint and can bedesigned, for example, as a control disk, a control cam or the like,such that a defined hydraulic reaction is initiated depending on theattained knee angle. A corresponding design can be provided for theankle joint. After a defined angle has been reached, the forcetransmission can then be interrupted or a movement reversal per switchcan take place in such a way that a dorsiflexion is initiated when apredetermined knee angle is reached. Also in the event of a movementreversal of the lower leg part in the swing phase, valve adjustment byswitching in such a way that a dorsiflexion is effected in an extensionmovement of the knee joint. If sensors are used which detect certainloads, movements, angles or other parameters, the detected sensor valuescan be used to control the force transmission, i.e. to permit orinterrupt a force transmission or transmit only some of the forces. Thesensors are coupled to the sensor mechanism, which receives the sensorsignals, processes them and, via an actuator, for example a valve, opensor closes in order to modify a flow of fluid.

A cylinder/piston unit can be arranged in each case on the upper part orthe thigh part and on the shin part or the lower part or foot part,which cylinder/piston units are connected to each other by at least onehydraulic line. As a result of the movement of the knee, pressure isexerted on the upper hydraulic unit and is carried via a correspondingline and, if appropriate, a valve block to the lower hydraulic unit inorder to actuate the foot part.

The cylinder/piston units are connectable to each other in parallel orcrosswise via valves. It is likewise possible for an individualadjustment, including blocking of the cylinder/piston units, to beperformed by the control mechanism in order to release or actuate thefoot part as a function of the respective knee setting, direction ofmovement, speed of movement, acceleration of movement or gait situation.

A sensor mechanism can be provided for detecting the knee angle, theangle velocity or angle acceleration, which sensor mechanism isconnected to a control mechanism for adjusting a valve or severalvalves, such that an electronically controlled valve switch is providedin order to control the hydraulic or mechanical transmission of force.

The force transmission mechanism can block a force transmission in thedorsiflexion direction, in order to ensure that a shift during thestance phase does not lead to unwanted flexion of the knee. Provisioncan be made that the maximum dorsiflexion position is variablyadjustable, i.e. a dorsiflexion abutment is provided which is adjustablein order to be able to adapt to the respective user or the conditions ofuse. The dorsiflexion abutment can be designed as a mechanical abutmentor can be realized by closing a valve.

A restoring device can be assigned to the foot part in order to effect adorsiflexion of the foot part. For example, the restoring device can bedesigned as a spring or elastomer element which counteracts a plantarflexion. The ankle joint can be designed as an elastic joint in which anelastic element, for example an elastomer body, is arranged, wherein arestoring force is applied by the elastic joint to the foot part, suchthat the foot part is moved back to the initial position without theaction for external forces.

In one embodiment, at least one damper, which counteracts adorsiflexion, is present in the ankle joint, such that a restoringmovement can be performed without overswing after a plantar flexion.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are explained in more detailbelow with reference to the attached figures, in which:

FIG. 1 shows ankle angle and knee angle profiles;

FIG. 2 shows a perspective view of a device;

FIG. 3 shows a side view of the device according to FIG. 2 in anextended position;

FIG. 3 a shows a perspective view according to FIG. 3 ;

FIG. 4 shows a device according to FIG. 3 in a flexed position;

FIG. 5 shows a block diagram of a hydraulic force transmission;

FIG. 6 shows a schematic view of a prosthesis device with a hydraulicunit;

FIG. 7 shows a perspective view of the embodiment according to FIG. 6 ;

FIG. 8 shows a mirror-image view of the embodiment according to FIG. 6 ;

FIG. 8 a shows a sectional view of FIG. 8 ;

FIG. 9 shows a sectional view of a cylinder/piston unit;

FIG. 10 shows a perspective overall view of a cylinder/piston unit;

FIG. 11 shows a cross-sectional view of an installed cylinder/pistonunit in the extended state;

FIG. 12 shows a device according to FIG. 11 with a flexion angle of 60°;

FIG. 13 shows a device according to FIG. 11 with a flexion angle of120°;

FIG. 14 shows a sectional view of a surface-side cylinder/piston unit inthe dorsiflexion position;

FIG. 15 shows an embodiment according to FIG. 14 in the plantar flexionposition;

FIG. 16 shows a schematic view of different switching possibilities;

FIG. 17 shows a schematic view of a valve arrangement;

FIG. 18 shows angles of the knee and of the ankle joint over time; and

FIG. 19 shows superposed angle profiles of the ankle joint over time.

DETAILED DESCRIPTION

FIG. 1 shows different angles over time during a gait cycle. The naturalknee angle KA and the natural ankle angle AA are shown by broken lines,the prosthetic knee angle PKA and the prosthetic ankle angle PAA areshown by solid lines over time during a step from heel strike to renewedheel strike. While the natural knee angle KA can be approximated veryclosely by a prosthetic device, as can be seen from the smalldifferential angle and from an almost congruent profile of the kneeangles KA and of the prosthetic knee angles PKA, the prosthetic ankleangle PAA deviates greatly from the natural ankle angle AA, the extentof the deviation being indicated by the differential angle DPF. Themaximum deviation is present, in approximately two thirds of the gaitcycle, shortly before toe-off when, in a natural gait phase, the maximumplantar flexion is ca. 30° starting from the initial position whenstanding, whereas the maximum plantar flexion in a prosthesis isapproximately 2°, which is caused by the dynamics of the foot.

To provide a gait pattern that is as natural as possible, a firstembodiment of an orthopedic device 1 in the form of a lower legprosthesis according to FIG. 2 is proposed, which has a knee joint 10with a proximal upper part 11 and with a lower part 13 secured thereonpivotably about a knee axis 12. On the distal lower part 13, a shin part14 is secured which provides a connection to the ankle joint 20 and ismounted on the foot part 23 so as to be pivotable about an ankle jointaxis 22. In the illustrative embodiment shown, the foot part 23 isdesigned as a seat for an adjustment core for a prosthetic foot and hasa jib 25 which, in the illustrative embodiment shown, is directedforward in the walking direction, i.e. has an anterior orientation. Thelower part 13 and the shin part 14 have slotted guides, such that thetwo components are mounted movably on each other, so as to be able tomake a length adjustment if this is desired or necessary. The lower part13 is composed of two side plates, which are secured on shin parts 14likewise designed as side plates, with the side plates lying congruentlyon each other. An abutment 16 for limiting the maximum extension angleis provided on the lower part 13, and an ankle abutment 26, which limitsthe maximum dorsiflexion of the foot part 23, is likewise provided onthe shin part 14.

Arranged on the upper part 11, which is mounted so as to be pivotableclockwise about the knee axis 12, there is a jib 15 which faces rearwardin the walking direction, i.e. has a posterior orientation, and in whichan oblong hole guide is formed in which a distal articulation point 17for a force transmission mechanism 3 is mounted. The articulation point17 is arranged movably inside the oblong hole guide and is fixed there,by an orthopedic technician, in the correct position for the patient.The exact set-up of the force transmission mechanism 3, which in thedepicted illustrative embodiment is designed as a mechanical couplingelement in the form of an articulated rod, will be explained in moredetail below.

The lower end of the coupling element is mounted in a distalarticulation point 27 on the distal jib 25 in an articulated butimmovable manner. By means of the arrangement of the articulation points17, 27 posterior and anterior of a connection line between the knee axis12 and the ankle joint axis 22, the clockwise rotation of the proximalarticulation point 17 mounted eccentrically with respect to the kneeaxis 12 means that a flexion of the knee joint 10 leads to a movement ofthe coupling element and to a rotation of the distal jib 25counterclockwise about the ankle joint axis 22, such that the foot part23, with the prosthetic foot (not shown) secured thereon, is flexed inthe plantar direction when the knee is flexed.

FIG. 3 , which is a sectional view from the side, shows the prosthesis 1according to FIG. 2 in an initial position, which corresponds tostanding. The knee joint 10 is located at the maximum extension, and thejib 25 of the ankle joint 20 is substantially at right angles to thelongitudinal extent both of the shin part 14 and also of the lower part13 and the connection line between the knee axis 12 and the ankle jointaxis 22.

The oblong hole guide for the proximal articulation point 17 can be seenon the distal jib 15, likewise the proximal lever length X, which can bevariably adjusted. The ankle lever length Y, which represents thedistance between the distal articulation point 27 and the ankle jointaxis 22, is indicated on the distal jib 25. The figure also showsclearly the mechanical force transmission mechanism 3 with a distalsleeve 30, which is mounted in an articulated manner on the ankle jib25, a double screw 31 with opposite threads, and a proximal sleeve 32,which is mounted on a bracket 35 so as to be pivotable about a hingeaxis 33. An abutment 34 formed on the bracket 35 prevents the proximalsleeve 32 from deflecting clockwise about the axis 33 beyond apredetermined angle.

FIG. 3 a shows the prosthesis 1 in a perspective view according to FIG.3 . It can be seen clearly from the perspective view that the ankle jib25 is designed as a fork that is open on one side and that has twobranches between which the distal sleeve 30 is mounted pivotably on thedistal articulation point 27. Both the distal sleeve 30 and also theproximal sleeve 32 have an inner thread into which the double screw 31is screwed. The proximal sleeve 32 is mounted about the hinge axis 33 onthe bracket 35, which in turn is secured on the proximal jib 15. Theupper part 10 is mounted via pins on the lower part 13 so as toarticulate about the pivot axis 12, and the abutment 34 prevents theproximal sleeve 32 from pivoting clockwise about the hinge axis 33beyond the fixed extent, which is defined by the abutment 34.

The mechanical dorsiflexion abutment 26, by means of which the maximumdorsiflexion of the foot part 23 is fixed, is secured on the shin part14. The dorsiflexion abutment 26 is adjustable, such that the maximumdorsiflexion can be variably adjusted.

FIG. 4 shows the prosthesis 1 in a flexed state. Whereas the knee angleα was 0° in FIG. 3 , a knee angle of approximately 50° is provided inFIG. 4 . The plantar flexion angle β, which was 0° in the positionaccording to FIG. 3 , is ca. 25° in FIG. 4 , which can be varied by thedifferent lever lengths X, Y in the respective jibs 15, 25. If the leverlength Y on the ankle jib 25 is also adjustable, the transmission ratio,in interaction with a length adjustment, can be performed easily via thedouble screw 31. The initial position, that is to say the plantarflexion angle β as a function of the knee angle α in the positionaccording to FIG. 3 , can be adjusted via the double screw 31 and theposition of the proximal articulation point 17 inside the oblong holeguide. When the double screw 31 is unscrewed from the threads in thesleeves 30, 32, the force transmission mechanism 3 lengthens, such that,with a constant position of the articulation points 17, 27, the footpart 23 is flexed in the plantar direction and, conversely, with anopposite direction of rotation, a dorsiflexion is initiated.

FIG. 4 shows, for the illustrative embodiment, the maximum knee angle αup to which a compressive force can be transmitted to the distal jib 25,by the force transmission mechanism composed of the two sleeves 30, 32,the double screw 31 and the bracket 35, without the distal sleeve 32pivoting about the axis 33. An abutment can be formed in the bracket 35;a further rotation of the bracket 35 relative to the jib 15 can likewisebe prevented by other mechanisms, such that, with a further flexion inthe knee joint 10, the distal end of the bracket 35 is shifted in theclockwise direction, such that buckling takes place in the forcetransmission mechanism 3, which leads to a shortening of the effectivelength between the two articulation points 17, 27. This leads to areduction of the plantar flexion angle β, which can be supported by apretensioning mechanism, for example in the form of a spring. As aresult of the reduction of the plantar flexion angle β, the effectiveleg length is reduced by the tip of the prosthetic foot (not shown)being moved in the dorsiflexion direction and lifted, such that aneasier swing through can take place in the swing phase if an extensionmovement is performed in the knee joint 10.

In principle, it is also possible for the jibs 15, 25 to be oriented inthe respectively reverse direction, i.e. the proximal jib 15 in theanterior direction and the distal jib 25 in the posterior direction, inwhich case the force transmission mechanism 3 works mainly bytransmitting tensile force when the knee joint 10 is flexed.

FIG. 5 shows a basic set-up of a hydraulic force transmission mechanism3. Here too, jibs 15, 25 are provided on the knee joint 10 and on theankle joint 20. In a very simple design of the knee joint 10, the lowerpart 13 can at the same time form the connection between the knee joint10 and the ankle joint 20. Generally, the knee joint 10 is designed as aseparate component and has an upper part 11 and a lower part 13, onwhich it is possible to secure, by securing means, a shin tube or shinpart 14, which in turn is fixed on securing means of the ankle joint 20of a prosthetic foot. In the illustrative embodiment shown, a firsthydraulic cylinder/piston unit 40 is mounted on the proximalarticulation point 17 and on the lower part 13. By way of hydrauliclines 42 that open into a valve block 43, a distal cylinder/piston unit41 is connected to the proximal cylinder/piston unit 40 in terms offlow. The distal piston/cylinder unit 41 is optionally mounted on thelower part 13 or on a shin part and also on the jib 25 at the distalarticulation point 27. When the knee joint 10 is flexed, the pistoninside the proximal piston/cylinder unit 40 moves downward, hydraulicfluid is conveyed through the line 42 into the valve block 43 and fromthere into the upper chamber of the distal piston/cylinder unit 41, suchthat a plantar flexion of the foot part 23 about the ankle joint axis 22is effected.

In the illustrative embodiment shown, the two hydraulic units 40, 41 aredesigned as two unidirectional cylinders, which are of the sameconfiguration in terms of volumes and diameters. An individualtransmission can be achieved by different levers on the knee joint 10and on the ankle joint 20.

A plurality of different valves can be provided in the valve block 43 soas to connect all the cylinder volumes to each other in any desiredmanner, in order to be able to set different plantar flexion angles 1 atdesired knee angle adjustments. Proportional valves may be presentinside the valve block 43, by means of which it is possible to performthrottling, such that different hydraulic resistances can be madeavailable. By different connection of the individual cylinders, it ispossible, depending on the type of movement and the phase of movement,to achieve a desired adjustment of the foot part 23 as a function of theknee angle α.

FIG. 6 shows a schematic side view of a prosthetic device with hydraulicforce transmission. Similarly to the illustrative embodiment accordingto FIG. 2 , an oblong hole guide is provided in the proximal jib 15, andthe upper articulation point 17 of the proximal piston/cylinder unit 40is mounted in said oblong hole guide. The lever length X, and thereforethe mechanical gearing, can be adjusted via a fixing mechanism. Apyramid adapter is secured on the upper part 11 of the knee joint 10,while vertically adjustable shin parts 14 are mounted on the lower part13 of the knee joint 10 with the side plates, between which the distalpiston/cylinder unit 41 is arranged. The lower articulation point 27 isrotatable but mounted non-displaceably on the distal jib 25 on whichsensors, for example in the form of strain gauges, can be arranged inorder to detect the load. The valve block 43 is provided with a controldevice 44 in which switching electronics are accommodated, such that thevalves arranged inside the valve block 43 can be used for differentcoupling of the cylinders in the cylinder/piston units 40, 41individually and after evaluation of sensor data.

FIG. 7 shows a perspective view of the illustrative embodiment accordingto FIG. 6 , from which view it can be seen that the hydraulic cylinderunits 40, 41 are arranged between the shin parts 14 and lower parts 13designed as side plates. The valve block 43 can likewise be arrangedbetween the side plates.

FIG. 8 shows a variant of the invention in which angle sensors 50 bothin the knee joint 10 and also in the ankle joint 20 are coupled to thecontrol unit 44, such that, as a function of the knee angle α and theplantar flexion angle β, the valves inside the valve block 43 can beswitched in an angle-dependent manner. It is likewise possible toprovide other sensors, for example position sensors or force or momentsensors, in order to determine the spatial position, forces or momentsand use these to control the valves.

FIG. 8 a shows a sectional view of FIG. 8 . In the upper part 11,mounted on the lower part 13 in an articulated manner about the pivotaxis 12, and in the extension abutment 16, the proximal jib 15 in FIG. 8a can be seen with the oblong hole guide for the proximal articulationpoint 17. A piston rod 420 of the proximal cylinder/piston unit 40 issecured on the proximal articulation point 17. A piston 410 is securedon the piston rod 420 and is guided in a housing 400 of thepiston/cylinder unit 40. In the completely extended position of the kneejoint 10 illustrated, the piston 410 of the proximal cylinder/pistonunit 40 is located on the proximal abutment. By way of hydraulic lines(not shown), which open into the valve block 43 and are opened,completely closed or partially closed by the control unit 44 viacorresponding valves, the hydraulic fluid is conveyed from the distalcylinder chamber to the distal cylinder/piston unit 41 during a flexionmovement. Starting from the neutral position shown, hydraulic fluid isconveyed into the proximal cylinder chamber of the distalcylinder/piston unit 41 when the knee joint 10 is flexed, such that thedistal piston rod 420 is shifted in the direction of the distal bearingpoint 27, such that a plantar flexion takes place about the ankle jointaxis 22.

FIG. 9 shows a detailed view of a piston/cylinder unit with a housing400, in which a piston 410 is secured on a piston rod 420. Two endabutments 430 limit the volume bounded by the housing 400. The cylindersformed by the housing 400 are closed by lids 440. Slide bearings 450 andwipers 460 are integrated in the lids 440. On each end of the twocylinders that are separated by the piston 410, hose attachments 470 areprovided, which are connected to hydraulic lines 42 (not shown). Abearing bolt 480 is arranged on the piston rod 420, which bearing bolt480 can be arranged in one of the articulation points 17, 27 of the jibs15, 25. The bearing bolt 480 can be provided as a joint head with twoaxial pins for bearing on the jibs 15, 25, while a second bearing pointis shown in the perspective view according to FIG. 10 . The axial pins490 in the housing 400 serve for bearing in the side plates either ofthe lower part 13 or of the shin part 14.

FIGS. 11 to 13 show a cross-sectional view of the proximalpiston/cylinder unit 40 in different knee angle positions. In theposition shown in FIG. 11 , the knee angle is 0°, and the piston 410inside the housing 400 is then located in the maximum position at theproximal end abutment. All the hydraulic fluid has been pressed out ofthe proximal cylinder, and the volume of the distal cylinder is maximal.

FIG. 12 shows a knee angle position with a knee angle α of 60°. Thepiston 410 is located past the middle of the housing 400, such that theproximal cylinder has a greater volume than the distal cylinder. By theflexion of the knee joint, the piston 410 has been moved downward insidethe cylinder, and hydraulic fluid from the lower cylinder has beenconveyed through the valves to the distal piston/cylinder unit 41 (notshown).

FIG. 13 shows a position of the knee joint with a knee angle α of 120°,as is adopted when kneeling down or squatting. The position of thepiston 410 corresponds to that of FIG. 12 , but the piston 410 hasalready reached the distal end abutment at a position of a knee angle αof 90°. The reverse movement of the piston 410 when passing through theknee angle of 90° can either lead to the reverse movement in the controlof the ankle joint 20 or can be compensated by a switching of thevalves.

FIG. 14 shows the arrangement of a piston/cylinder unit 41 on the anklejoint 20 with a dorsiflexion in which the piston 410 is positioned closeto the proximal end abutment 430. FIG. 15 shows an ankle joint 20 atmaximum flexion, for example at a knee angle α of 90°.

FIG. 16 shows a schematic view of different switching possibilities. Thehose attachments 470 can be switched in parallel, and it is likewisepossible that the hose attachments 470 of the distal piston/cylinderunit 41 are switched crosswise with the hose attachments 470 of theproximal piston/cylinder unit 40. It is likewise possible that thepiston/cylinder units 40, 41 are switched independently of each other,such that no functional connection is present between the units. Theknee joint 10 and the ankle joint 20 are therefore freely movableindependently of each other; if appropriate, the damping in the kneejoint 10 and/or the ankle joint 20 can be adjusted via a throttle valve.If the proximal piston/cylinder unit 40 is switched free while thedistal piston/cylinder unit is blocked, the knee joint 10 is freelymovable and the ankle joint 20 is rigid, and, when both piston/cylinderunits 40, 41 are blocked, both joints are rigid.

By virtue of the controlled flexion and extension in the ankle joint 20as a function of the knee angle α and a coupling of the plantar flexionas a function of the knee flexion, it is possible to use the kineticenergy of the knee for the ankle movement. This achieves a lengtheningof the effective leg length in the knee flexion at the end of the stancephase, and in this way the duration of the ground contact is lengthened,as a result of which the vertical movement of the center of gravity ofthe body during walking is minimized. This results in an approximationto the natural gait pattern. By virtue of the dorsiflexion in the swingphase, it is possible again to shorten the effective leg length in orderto minimize the likelihood of stumbling. On account of the directconversion of the mechanical energy with minimal loss of performance, itis possible to attain a high level of energy efficiency with arelatively low weight when compared to known orthotic devices, inparticular prostheses with motorized adjustment mechanisms.

In FIG. 17 , the two cylinder/piston units 40, 41 assigned respectivelyto the knee joint and to the ankle joint are each shown schematically inthe neutral position. The piston rod 420 protruding in each case fromthe housing 400 is secured, for example, on the respective jibs 15, 25in order to permit a force transmission, while the other end of thepiston/cylinder unit is mounted on the lower part or shin part.

The hydraulic lines 42 connect the cylinder chambers to each other inparallel, the hydraulic lines 42 are connected to each other bytransverse lines, and a diagonal line connects a cylinder chamber facingaway from the piston rods 420 to a cylinder chamber of the distalcylinder/piston unit 41 facing toward the piston rod 420.

At least one valve 431, 432, 433, 434, 435, 436 is arranged in each ofthe hydraulic lines 42 in order to be able to perform differentswitching procedures. For example, if the valves 433, 434, 435 areopened and the other valves 431, 432, 436 are closed, a parallelswitching is obtained, which has the effect that a displacement of theupper piston 410 to the left leads to a displacement of the lower piston410 to the right. In order to generate an opposite movement, thecylinder/piston units 40, 42 have to be switched crosswise, for whichpurpose the valves 431, 434 and 435 are closed while the valves 432, 433and 436 are open.

When the valves 433, 434 and 436 are closed, this leads to a decouplingof the proximal piston/cylinder unit 40 from the distal cylinder/pistonunit 41. By partial closure of the opened valves 431, 432 and 435, it ispossible to adapt the resistance to displacement.

If only the upper valve 431 is opened, the ankle joint remains rigid,whereas the knee joint can be flexed, the resistance to the flexionarising from the hydraulic resistance of the opened valve 431. A rigidknee joint and movable ankle joint is possible if the valves 432, 435are opened and the other valves remain closed.

FIG. 18 shows the profile of the knee angle KA and of the ankle angle AAin a prosthetic knee joint with a coupling device according to theinvention during a gait cycle. After the heel has been set down, theso-called heel strike, a plantar flexion PF of the ankle joint takesplace counter to a spring force for example, which holds the ankle jointin the initial position. The plantar flexion after the heel strike iseffected by the transmission of forces from the knee flexion by way ofthe force transmission mechanism and superposes the force of therestoring spring acting in the direction of a dorsiflexion which, in thefurther profile, after approximately a quarter of the step duration,leads to a cancelling of the forces acting in opposite directions. Theankle joint angle is then 0° again. In the knee joint there is aninitial stance phase flexion with simultaneous reduction of the anklejoint angle after reaching an initial local maximum at ca. 10% of thestep duration. After the maximum extension of the knee joint is reached,the force introduction point migrates in front of the ankle joint afterapproximately one third of the step duration, as a result of which thereis a dorsiflexion DF. After approximately half of the step duration, theknee angle KA increases, while at the same time a plantar flexion isinitiated which, with flexion of the knee, conveys the arising forces tothe ankle joint. After approximately two thirds of the step duration, adecoupling DC of the ankle joint from the knee joint takes place, suchthat the knee joint can swing freely rearward, while the ankle joint ismoved back to the initial position after reaching the maximum plantarflexion. On account of a damper not present, this return movement takesplace in the form of an attenuating oscillation.

FIG. 19 shows different profiles of the ankle joint angle during thecourse of a step, wherein the curves A and B show angle profiles thatare obtained with a device according to the invention, and curve C showsthe profile of a conventional ankle joint. At the end of the groundcontact GC, i.e. at the end of the terminal stance phase, the curves Aand B reach a plantar flexion angle of between 8° and 10°, whereas aconventional ankle joint has a dorsiflexion of ca. 8°. After thedecoupling DC of the force transmission mechanism from the ankle joint,a relatively quick dorsiflexion takes place on the curve B, since nodamping mechanism is present there, the curve A provides damping, and inthe curve C, after the end of the ground contact, the initial state isreached very quickly again.

The invention claimed is:
 1. An orthopedic device, comprising: a knee joint, comprising: a proximal upper part configured to be fastened to a patient; a distal lower part pivotally connected to the proximal upper part about a knee pivot axis; an ankle joint; a foot part connected to the ankle joint; a shin part extending between the ankle joint and the knee joint; a force transmission mechanism connected to the foot part and to the proximal upper part of the knee joint, the force transmission mechanism being operable to provide a plantar flexion of the foot part when the knee joint is flexed, the force transmission mechanism comprising an articulating rod that transmits at least one of tensile force and compressive force, and wherein the articulating rod is configured to buckle in one direction only.
 2. The orthopedic device as claimed in claim 1, wherein the articulating rod is a mechanical coupling mechanism.
 3. The orthopedic device as claimed in claim 1, wherein the articulating rod is mounted to the upper proximal part at a first bearing point positioned proximal of the knee pivot axis, and is mounted to the distal lower part at a second bearing point distal of an ankle pivot axis of the ankle joint.
 4. The orthopedic device as claimed in claim 3, wherein the first and second bearing points lie on different medial/lateral sides of a connection line extending between the knee axis and the ankle joint axis.
 5. The orthopedic device as claimed in claim 3, wherein at least the first bearing point is adjustable.
 6. The orthopedic device as claimed in claim 3, wherein the force transmission mechanism has a control mechanism, and the control mechanism is coupled to at least one sensor in order to control a force transmission in accordance with sensor values.
 7. The orthopedic device as claimed in claim 1, wherein the force transmission mechanism comprises a control mechanism operable to stop or reverse transmission of the at least one of tensile force and compressive force upon reaching a predetermined knee flexion angle.
 8. The orthopedic device as claimed in claim 1, wherein the force transmission mechanism has a control mechanism in order to permit or interrupt a force transmission.
 9. The orthopedic device as claimed in claim 1, wherein the force transmission mechanism blocks a force transmission in a dorsiflexion direction.
 10. The orthopedic device as claimed in claim 1, wherein a maximum dorsiflexion position of the foot part is designed to be variably adjustable.
 11. The orthopedic device as claimed in claim 1, wherein a restoring device is assigned to the foot part in order to effect a dorsiflexion of the foot part.
 12. The orthopedic device as claimed in claim 1, wherein the ankle joint is designed as an elastic joint and exerts a restoring force in the event of an excursion from a starting position.
 13. The orthopedic device as claimed in claim 1, wherein at least one damper is positioned in the ankle joint, the at least one damper counteracting a dorsiflexion.
 14. The orthopedic device as claimed in claim 1, wherein the orthopedic device is a prosthesis or orthosis.
 15. The orthopedic device as claimed in claim 14, wherein the force transmission mechanism is connected to the proximal upper part of the knee joint at a location spaced proximal of the knee pivot axis.
 16. The orthopedic device as claimed in claim 14, wherein orthopedic device is an orthosis, and the orthosis comprises a knee joint, an ankle joint, a lower leg rail, a foot part, and a thigh component or thigh rail.
 17. The orthopedic device as claimed in claim 1, wherein orthopedic device is an orthosis, and the orthosis comprises a knee joint, an ankle joint, a lower leg rail, a foot part, and a thigh component or thigh rail. 